This invention relates generally to water craft, and more particularly to a water board craft having a fin that is adjustable to a plurality of angular positions with respect to the direction of travel of the water craft. This invention is particularly useful when applied to a surfboard or sailboard to allow the rider to adjust the performance of the board to adapt to changing surf conditions and to variations in the weight and skill level of the rider.
Water board craft are well known in the art, taking the form of surfboards, sailboards, boogie boards, and other similar water craft that are maneuvered by the shifting of the weight of the rider. Such water craft typically include a board, formed of a strong yet buoyant material or combination of materials, and one or more fins attached to the bottom of the board. The fins provide stability to the board as it moves through or is propelled through the water. It has been long recognized that an adjustably mounted fin may provide improved performance by allowing the rider to adapt the board to varying conditions.
U.S. Pat. No. 5,493,989 issued to Anderson on Feb. 27, 1986, teaches an adjustable fin box system wherein the fin may be adjusted in the vertical, horizontal and angular directions. However, the angular freedom of movement provided by the Anderson device is about a horizontal axis, providing adjustment of the fin angle along the longitudinal axis of the board. The device of Anderson provides no freedom of movement for the fin about a vertical axis to adjust the fin angle with respect to the direction of movement of the board through the water.
U.S. Pat. No. 4,854,904 issued to Wahl on Aug. 8, 1989, teaches a sailboard with an adjustable keel mechanism. The Wahl device is designed to allow the keel to pivot about a vertical axis during the use of the board in response to loads imposed against the keel by the water, thereby eliminating crabbing and improving the speed of the board. The Wahl device does not provide the desired security of position of a fin in a variety of predetermined angular position.
U.S. Pat. No. 5,567,190 issued to Oates on Oct. 22, 1996, teaches another fin box assembly for a surfboard that permits the fin to be adjusted within an elongated fin box attached to a board. While the Oates device does provide for adjustment of the fin about a vertical axis, the range of adjustment is limited by the width of the fin box. Furthermore, the security of the fin position depends upon a friction interference between parts. These features may limit the usefulness of the Oats device and reduce its dependability in real world conditions.